Grinding machine



Oct; 20, 1931. w. J. VBAUMBERGER 1,828,384

GRINDING MACHINE Filed Jan. 18, 1929 4 Sheets-Sheet l h; is ,INVENTOR ATTORN Y$ Oct. 20, 1931. 'w. J. BAUMBERGER GRINDING MACHINE Filed Jan. 18. 1929 4 Sheets-Sheet 2 Oct. 20, 1931. w. J. BAUMBERGER GRINDING MACHINE 4 Sheets-Sheet 5 Filed Jan. 18," 1929 Oct. 20, 1931.

w. J. BAUMBERGER 1,828,384

GRINDING MACHINE Filed Jan. 18, 1929 .4 Sheets- Sheet 4 INVENTOR ATTOR Y5 UNITED sTATE-S' 7 set forth'in the appended claims, together Patented Oct. 20, 1931 WILLIAM J.

new FFFICE i earner-Ne MAcHmn Application filed January 18', 11939. Serial no. 333.475.

This invention relates to orbital grinding machines and. particularly to grinding ma chines such as used for grinding cylindrical bores in which the grinding wheel spindle is journaled" ec'centric'ally in a rotating head with its axis parallel to the axis of the head so that the grinding wheel is revolved bodily about the axis of the headd'uring rotation of the head;

The present invention has for an object to provide means by which the grinding wheel spindle may be quickly and easily adjusted toward or away from the axis of the head during rotation of the head to change the radius of orbital movement to any desired ex-j tent within the limits of adjustment.

A further object isto provide a spindle adjusting mechanism which is operated bythe rotating head and which ismanually controllable so that the exact adjustment required maybe obtained. 8

A further object is to provide a-single spindle shifting mechanism which ,may be manually controlledto adjust the "spindle radially to the desired distance from the axis of the head and which may be automatically operatedto impart a slow feed movement to the grindingwheel spindle during the grinding operation.

A furtherobject is to provide a spindle adjusting gear." train which ismounted on'the head to rotate bodily therewith and which .may be operated by'holding a .gear of the train against rotation with the head.

I A further object is to provide meansby whichthe gear train may be operated-continuously toobtain a desired adjustment of the spindle andby which slightmovements may be intermittently imparted to the gear train to impart a very slow feed movement to the grinding wheel spindle during the operation of the machine.

. NVith the above and other objects iniview, the invention may be said. to comprise the device as illustrated in the accompanying drawings hereinafter described and particularly with such variations and modifications thereof as will be apparent to one skilled in the art to which the invention appertains.

BAUMBERG-ER, OF DAVENPORT, IOWA, ASSIGNOR TOMIGRO MACHINE COM- 1 Reference should be had to the accompany- 7 ing' drawings forming a part of this specification in which'i H v j" Figure 1 is a longitud nal vertical section takenaxiallythrough the head of an orbital grinding inachine embodying the invention, the upper half of the head between the front and rearbearings being shown in elevation.-

F ig; 2 is a transverse vertical section through the head.

mounted exteriorly on the rotating head.

" Fig. 4: is asection taken on the line indicated at t-lin Figs. 2 and 3. p

' Fig. .5 isa section taken on the line indicated at 55 Fig.2.

whichthere is journaled a rotatable head 2 which has a longitudinal eccentric bore 2 in which there is r'ot'atablymounted a bearing sleeve 3 which has an" eccentric bore 4 which receives the grinding wheel spindle.

tween thebearings 1 the head 2 has fixed thereto a large gear 5 through which continuous rotation may be imparted to the head during the operation of the machine.

.Theframe 1 is provided with a housing 6 between the "bearings 1 which encloses the gear 5 and other mechanism to be hereinafter described. p l

The grinding wheel spindle is supported in 5 Fig.3 1s a detallview showlng the gearing 0 vided with suitable spaced bearings 1 in the sleeve3 eccentrically with respect to the head 2 so that the rotation of the head causes the grinding Wheel spindle to have an orbital movement about the axis of the head. By rotating the bearing 3 within the head 2, the

be positioned to "operate upon cylindrical'internal surfaces of diiierent diameters.

to obtain the desired adjustments, the turning movement being imparted to the bearing The present invention provides means for turning the bearing sleeve 3 wlt'hin the head 9 grindlng wheel spindle whlch 1s eccentr1-' sleeve through suitable gearing carried by the head.

As shown in Figs. 1 and 2, the bearing sleeve 3 has fixed thereto a worm gear 7 which meshes with a worm 8 fixed to a shaft 9 which is mounted in a chordal bore 10 in a head 2. Within the bore 10, beyond the inner end of the shaft 9, there is mounted a cap 11 which supports a bearing 12 for the inner end of the shaft. The opposite end of theshaft 9 is supported in a bearing sleeve 13 which has a counter bore 14 at its innerend to receive a bearing 15 adjacent the worm 8 and av counter bore 16 at its outer end to receive thrust bearings 17 and an end bearing 18, the end bearing 18 being retained by a cap 19 secured to the outer end of the sleeve.

The shaft 9 projects through the sleeve 13 to the exterior of the head, and at. its outer end has fixed thereto a worm gear 20 which meshes with a worm 21 fixed to a shaft 22 which is parallel with the axis of the head and which is journaled in roller thrust bearings (see Fig. 4) mounted in bearing brackets 24 which are bolted or otherwise firmly secured to the periphery of the head.

The worm 21 is mounted between the thrust bearings 23 and the shaft 22 projects at both lIldS beyond the bearings. At one end thereof, the shaft 22 has fixed thereto a pinion 25 which meshes with a large ring gear 26 which is rotatably mounted upon the head. The ring gear .26'has a flange 27 provided on its outer face with regularlyspaced stop lugs 28 by means of which the ring gear may be held against rotation with the head 2 as will be hereinafter explained. At its opposite end, the shaft 22 has fixed thereto a pinion 29 which meshes with a pinion 30 on a counter shaft 31, parallel with the shaft 22 which is journaled in roller thrust bearings 32 mouted in a bearing bracket 33 bolted or otherwise firmly secured to the head. The pinion 30 also meshes with a large ring gear 34 similar to the ring gear 26 which is r0- tatably mounted upon the head and which is provided with a flange 35, the outer face of which has spaced stop lugs 36 corresponding to the lugs 28 above referred to.

It will be apparent that the gear train above described connects the bearing sleeve 3 with the two ring gears mounted upon the head and that, normally duringthe rotation of the head, the two ring gears 26 and 34 will turn with theheadand there will be no rotation of the individual gears in the train connecting these ring gears with the bearing sleeve 3. However, if either of the ring gears 26 or 34 be given a movement of rotation with respect to the head 2, the gear train will be actuated and cause the bearing sleeve 3 to turn about its axis.

It will also be apparent that the gearing connecting thetwo ring gears 26 and 34 is such that rotation of one of the ring gears with respect to the head will cause rotation of the other in the opposite direction with respect to the head. If, while the head is rotating, one of the ring gears is held against movement, the pinion meshing with the ring 3 feed the spindle during the operation of 5 the machine. To this end, means is provided for imparting to the gear train a very slight movement at intervals during the rotation of the head. This intermittent movement is imparted to the gear train through a ratchet 37 fixed to the shaft 31, the ratchet 37 being engaged by a pawl 38 carried by a rocker arm 39 pivoted on the shaft 31. The lOCl fGI arm 39 is normally held in retracted position means of a spring 40 and is provided with a laterally extending actuating arm 41 by means of which the rocker arm may be rocked in a direction to impart an angular movement to the ratchet 37 and shaft 31, which movement is transmitted through the gear train to the bearing sleeve 3 The ratchet feed above described is suitable only for slowly increasing the depth of out during the operation of the machine. It

is, therefore, desirable that means be provided by which the grinding wheel may be quickly adjusted while the head is rotated toward or away from the axis of the rotatable head, so that the operator before entering the grinding wheel into the surface to be 1:

ground may quickly set the grinding wheel at approximately the correct position for engagement with the wall of the bore and so that at any time during the grinding operat on, the grinding wheel may be quickly shifted out of contact with the work. The relatively rapid adjustments of the grindmg wheel are obtained by holding one or the other of the ring gears 26 and 34 against rotati'on, manually operable means being provided forengaging and holding either of the gears. I

As shown in Figs. 1, 2 and 5, the holding means consists of a pair of vertically movable stop pins 42 and 43 slidably mounted in vertical guide standards 44 and 45 mounted onthe frame beneath the head 2. The stop pins 42 and'43 have enlarged lower ends 46' and 47 provided with notches 48 and 49 which receive the round heads 50 and '7 Adjacent their outer'ends, the rockshafts 54 have arms 58 and'59 attached thereto which are connected by links 60 and 61 to the op- "ypositc ends of a rocker arm 62 which is attached at its center to a-shaft 6,3 journaled in a boss 64 formed integrally with the closure member 57 and extending to the exterior of the housing. Outside the housing, ahandle 65 is attached to the shaft 63 by means of which the shaft 63 may be turned in either direction from a neutral position. When the handle 63 is swung in one direction, the stop pin 42 is moved upwardly into the path of one of the lugs 28 of the ring gear 26 to hold the ring gear 26 against rotation with the head and, when the handle 65 is swung in the opposite direction, pin 43 will be moved upwardly into engagement with a lug 36 of the ring gear 34 to hold the ring gear 34 against rotation, onestop pin being moved downwardly while the other is being moved upwardly into engaging position.

Normally, both stop pins 42 and 43 are clear of the ring gears and means is preferably providedfor positively retaining the stop pins in inoperative position except 'when shifted by actuation of the handle 65. To this end, the links and 61 are provided with inwardly projecting lugs 66 and 67 which overlap between the rock shafts 54 and 55. The two lugs 66 and 67 normally rest upon the top of a plunger 68 which is pressed upwardly by a spring '69. The links 60 and 61 are thus caused to normally assume the position in which the lugs 66 and 67 both engage the plunger 68 and since the links 60 and 61 are of equal length, the actuating arm 62 will occupy a horizontalposition, as-shown in Fig. 1. The pins 42 and 43 are of a length such that in the normal positions in which the rock shafts 54 and 55 are held by the spring plunger 68, the upper ends of both pins are clear of the lugs 28 and 36. If the handle be swung in one direction, the link 60 will be depressed, pushing the plunger 68 downwardly and the links 61 will be lifted away from the plunger. Depression of the link 60 will rock the shaft 54 in a direction shaft 55 in a direction tolift the stop pin 43 into engagement with the ring gear 34 while 7 the pin 42 is being moved downwardly from its normal position. Upon release of the handle 65, the spring plunger 68 will return both ro'ek'sliafts to normal positionand both stop pins will beheld clear of the lugs. Rotation of the bearing sleeve3 in one direction moves the axis of thegrindingspindle .to-

ward the axis of the head-and rotationof the bearing sleeve inthe opposite direction moves the grinding wheel spindle away from the axis of the head.

' As above explained, the two ring gears 26 and 34 are geared together for opposite rotation in the gear train so that when one of the ring gears is held, the spindle is adjusted inwardly toward the axis of the head and when the other ring gear is held, the spindle is adjusted outwardly away from the axis of the head. i

The two worm gearings in the gear train bearing sleeve with respect to the rotation of the ring gear on the head, so that the actual the workduring the operation of the ma chine. The automatic actuation of the pawl and ratchet mechanism is effected by means ofpins 70 and 71 which may be moved selectively into the path of movement of the projectingarm 41 of the pivoted pawl carrier so that a small angular movement is imparted to the ratchet and through the reduction gearing to the bearing sleeve 3.

The two pins 70 and 71 are mounted at different distances from the axis of the head so that one imparts a greater angular movement to the rocker arm than the other. The

pin 70, which is closer to the axis of the head is used to impart a coarse feed to the grinding wheel spindle andthe pin 71 which is farther from the axis is used to impart a fine feed, the angular movement of the ratchet 37 being greater when the arm 41 is actuated by the pin 70 since the arm 41 has to. turn through a greater angle to clear the pin.

7 As best shown' 'in Fig. 6,;the pins '70 and 71 have enlarged inner ends 72 and 73 which slide in bores 74 and 75 formed in a'housing 76 bolted to a bracket 77 formed integrally with the frame within the housing 6. The opposing faces of the enlarged portions 72 and 73 of the pins are flattened and provided with rack teeth78 which are engaged by a pinion 79 fixed to a shaft 80 which extends transversely into the housing 76 and through a side wall of the gear housing 6, the outer end of the shaft 80 being journaled in a bearing 81 in the wall of the housing 6 and having a handle 82attached to its outer-end outside greatly reduce the speed of rotation of the 1 the housing 6. By turning the handle 82 in one direction from a neutral position, the pin may be projected into the path of the arm ll and by turning the handle 82 in the opposite direction, the pin 71 may be projected into the path of the arm 41.

Means is preferably provided for normal- 1y holding both pins in an inoperative position and to this end, the enlarged portions 7 2 and 73 of the pins are provided with shoulders83 and 84, which engage with a plate 85 which is slidably mounted on a bolt 86 parallel withthe pins and secured to the housing 76outside the path of the arm 41. Be-

tween the head 87 of the bolt 86 and the plate 85, there is interposed a coil spring 88 which'presses the plate 85 toward the shoulders 84. When the pin 7 -1 is advanced toward engaging position, the shoulder 83 pushes p the plate 85-out-wardly against the spring 88 while the shoulder 84: moves rcarwardly away from theplate.

When the shaft is actuated in the opposite direction to advance the pin70, the

\1 shoulder 84 pushes the plate outwardly against the'spring 88 and the shoulder 83 moves inwardly away from the plate. Upon release of the-handle 82, the projecting pin is returned tothe normal position shown in Fig. 6 in which the plate 85 engages both shoulders SSE-and 84;.

' ationof the machine.

Furthermore, it is to be understood that the particular form of apparatus shown and described, and the particular procedure 'set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in theapp'ended claims.

What I claim is:

1. In an orbital grinding machine, a rotatable head,a spindle member eccentric-ally and rotatably mounted in the head and adapted to eccentrically support a spindle,

means for driving the head, a gear coaxial with the head and rotatably mounted thereon, a gear fixed to said spindle carrying member, reduction gearing carried by the rotatable head and forming a driving connection between said gears, and means for causing said first mentioned gear to turn wlth respect to the headto turn said spindle Carrying member in the head.

2. In an orbitalgrinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a gear coaxial with the head and rotatably mounted thereon, a driving connection between said gear and spindle carrying member, and releasable means engageable with said gear for holding said gear against rotation with the head to turn said bearing in the head.

3. In an orbital grinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a gear coaxial with the head and rotatably mounted thereon, a worm gear fixed to said spindle carrying member, a shaft mounted in said head, a worm fixed to said shaft and meshing with said worm gear, gearing connecting the first mentioned gear with said shaft, and means for causing said first mentioned gear to turn with respect to the head to impart a rotative movement'to said shaft.

i. In an orbital grinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a gear coaxial with the head and rotatably mounted thereon, a worm gear fixed to said spindle carrying member, a shaft mounted in said head, a worm fixed to said shaft and meshing with said worm gear, gearing connecting the first mentioned gear with said shaft, and releasable means for holding said first mentioned gear against rotation with the head to impart a rotative movement to said shaft.

5. In an orbital grinding machine, a 1'0- tatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a pair of gears coaxial with the head and rotatably mounted thereon, a pair of shafts having their axes parallel with the axis of the head and mounted upon the head, a pinion fixed to one of said shaft-s meshing with one of said gears, a pinion fixed to the other shaft meshing with the other of said gears, intermeshing pinions fixed to said shafts, ,a driving connection between one of said shafts and said spindle carrying member, and means for releasably holding either of said gears against rotation with the head. i

6. In an orbital grinding machine, a rotata ble' head, a spindle member eccentric-ally and rotatably mounted in the head and adapted to eccentri-cally support a spindle, means for driving the head, apair of ring gears rotatably mounted on the head gearing interposed between said gear-s which constrain said gears to opposite rotation with respect to the head, said gearingbeing mountedin bearings attached to the head, means operated by said gearing for turningsaid spindle carrying member in the head, and releasable means for holding either of said gears against rotation with the head. 1

7-; In anorbital grinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for drivingthe head, a pair of ring gears rotatably mounted on the head, gearing interposed between said gears which con strain said gears to opposite rotation with respect to the head, said gearing being mounted in bearings attached to the head, means operated by said gearing for turning said spindle carrying member in the head, releasable means for holding either of said gears against rotation with the head, and separate means for intermittently actuating said gearing.

8. In an orbital grinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a pair of rings rotatably mounted on the head, a shaft journaled in bearings attached to the head, driving connections between said shaft and each of said rings constraining said rings to rotation in opposite directions with respect to the head, a driving connection between said shaft and said spindle carrying member, and

means for releasably holding either rin against rotative movement with the head to drive said shaft. 7 p

9. In an orbital grinding machine, a rotatable head, a spindle member eccentrically and and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, apairof rings rotatably mounted on the head, a shaft j ournaled in bearings attached to the head, driving connections between said shaft and each of said rings constraining said rings to rotation in opposite directions with respect to the head, a driving connection between said shaft and said spindle carrying member, manually controlled means for causing said rings to turn on the head to turn said shaft in either direction, and independent manually controlled means for imparting intermittent turning movements to said shaft.

10. In an orbital grinding machine,arotat-- able head, a spindle member eccentrically and and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a pair of rings r0 tatably-mounted on the head, a-shaft journaled in bearings attached to the head, driving connections between saidshaft and each of said rings constraining said rings to rotation in opposite directions with respect to the head, a driving connection between said shaft andsaid spindle carrying member, means for, releasably holding either ring against rotative movement with the head to drive said shaft, and independent means for actuating said shaft. r

11. In an orbital grinding machine, a rotatable'head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle,

means for driving the head, a pair of rings rotatably mounted on the head, ashaft jour naled in bearings attached to the head, driving connections between said shaft and each of said rings constraining said rings to rotation in opposite directions, with respect to the head, a driving connection between said shaft and said spindle carrying member, means for releasably holding either ring against rotative movement with the head to drive said shaft, and means for automatically 1mpart1ng mtermlttent turnmg movements to said shaft during rotation of the head.

12. In an orbital grinding machine, a rotatable head, a spindle member eccentrically g releasably holding either ring against rotative movement with the head to drive said shaft, means for automatically imparting intermittent turning movements to said shaft during rotation of. the head, and meansfor controlling said automatic means to vary the rate of rotation of said shaft.

13. In an orbital grinding machine, a rotatable head, a spindle member eccentrically and rotatably mounted in the head and adapted to eccentrically support a spindle, means for driving the head, a pair of rings rotatably'mounted on the head, a shaft journaled in bearings attached to the head, driving connections between said shaft and each of said rings constraining said rings to rotation in opposite directions, with respectto the head, a driving connection between-said shaft and said spindle carrying member, a

pair" of stop members, each mounted for movement into and out of engagement with one of said rings, means for normally. hold- 'ing said stop members out of engagement with the rings, and manually operable means for shifting either of said stop members into engagement with its ring." I '14. In an orbital grinding machine, a supporting frame, a head rotatably mounted in said frame, a spindle carrying member rotatably mounted in the head, eccentrically thereof and adapted to eccentrically support a spindle, means for driving the head, a pair of rings rotatably mounted on the head, a shaft journaled in bearings attached to the head, driving connections between saidshaft and each of said rings constraining said rings to rotation in opposite directions with respect to the head, a driving connection between said shaft and spindle carrying member, a pair of stop pins mounted in the frame, each movable into and out of engagement with one of said rings, a rock shaft for actuating each of said pins, means for normally holding said pins out of engaging position, and a manually operable lever for selectively operating said rock shafts.

15. In an orbital grinding machine, a nipporting frame, a head rotatably mounted in said frame, a spindle carrying member rotatably mounted in the head eccentrically thereof and adapted to eccentrically support a spindle, means for driving the head, a pair of rings rotatably mounted on the head, a shaft journaled in bearings attached to the head, driving connections between said shaft and each of said rings constraining said rings to rotation in opposite directions with respect to the head, a driving connection be tween said shaft and spindle carrying member, a pair of stop pins mounted in the frame, eachmovable into and out of engagement with one of said rings, a pair of parallel rock shafts each connected 'to one of said pins, a lever connected to said rock shafts for si multaneously turning the same in opposite directions,and a spring acting on said rock shafts for normally holding said shafts in positions in which said pins are out of engagement with said rings.

16. In an orbital grinding machine, a rotatable head, means for driving said head, a spindle carrying member rotatably mounted in the head eccentrically thereof and adapted to eccentrically support a spindle, a train of gears comprising a gear rotatable on the head, a gear fixed to said spindle carrying member and-intermediate gears mounted on the head and constrained to rotate bodily thcrewitln and means for releasably holding the first mentioned gear against rotation with the head to drive said intermediate gears and turn said spindle carrying member in the head.

17. In an orbital grinding machine, a rotatable head. means for driving said head, a spindle carrying member rotatably mounted inthe head eccentricall thereof and adapted to eccentrically support a spindle, a train of gears mounted on the head and rotatable bodily therewith, said gear train including a gear fixed to said carrying memberand a pair of ring gears rotatably mounted on the head, the latter gears being connected in said train for rotation in opposite directions, and means for releasably' holding either of said ring gears against rotation with the head to' actuate said gear train.

18. In an orbital grinding machine, a rotatable head, means for driving said head, a

spindle carrying member rotatably mounted I in the head eccentrically thereof and adapted to eccentrically support a spindle, a train of gears mounted on the head and rotatable bodily therewith, said gear train including a gear fixed to said spindle carrying member and a pair of ring gears rotatably mounted on the head, the latter gears being connected in said train for relative rotation in opposite directions, and manually controlled means for causing said ring gears to rotate relatively to the head to drive said gear train in either direction.

19. In an orbital grinding machine, a rotatable head, means for driving said head, a spindle carrying member rotatably mounted in the head eccentrically thereof and adapted to eccentrically support a spindle, a gear train mounted on the head and rotatable bodily therewith. said gear train incluollng a gear fixed to said spindle carrying member and a pair of ring gears rotatable on said head, said ring gears being connected in-said train for rotation in opposite directions, manually cont'rolledmeans for causing said ring gears to'turn with respect to the head to drive said gear train in either direction to adjust said spindle carrying member, and separate manually controlled means for intermittently actuating said gear train to impart a feed movement to the spindlebearing.

20. In an orbital grinding machine, a rotatable head, means for driving said head, a spindle carrying member rotatably mounted in the head'eccentrically thereof and adapted to eccentrically support a spindle, gearing interposed between said rotatable head and said-spindle carrying member, andmanually controlled means for establishing a direct driving connection through said gearing from said head to said spindle carrying member to apply power from said head to said spindle carrying. member through said gearing to turnsaid spindle carrying member in the head.

21. In an orbital grinding machine, a rotatable head, a spindle carrying member adjustably mounted in the head, means for actuating said spindle carrying member including a shaft 'journaled in the rotatable head and extending transversely of the axis of the head, a ring gear coaxial with the head, and rotatably mounted thereon, means forming a driving connection between said ring gear and shaft, and manually controlled means operable during rotation of the head for causing said ring gear to turn with respect to the head to impart a rotative movement to said shaft;

22. In an orbital grinding machine, a rotatable head, a spindle carrying member adjustably mounted in the head, means for actuating said spindle carrying member including a shaft journaled in the rotatable head and extending transversely of the axis of the head, a ring gear coaxial with the head and rotatably mounted thereon, means forming a driving connection between said ring gear and shaft, and means operated by the rotating head for intermittently imparting turning movements with respect to the head to said ring gear to impart turning movements to said shaft.

23. In an orbital grinding machine, a rotatable head, means for rotating saidhead, a spindle carrying member eccentrically and shiftably mounted in said head and arranged to support a spindle, a pair of ring gears rotatably mounted on said head, bearings attached to said head, gearing mounted in said bearings and interposed between said gears which constrain said gears to rotate in opposite directions with respect to said head, means operated by said gearing and having connection with said spindle carrying member for bodily shifting said spindle'carrying member relative to said head, and releasable means for holding either of said ring gears against rotation with said head.

24. In an orbital grinding machine, a rotatable head, a spindle carrying member eccentrically and movably mounted in said head and arranged to support a spindle, means for rotating said head, a shaft, journal bearings secured to said head for supporting said shaft, a driving connection between said shaft and said spindle carrying member, a pair of rings rotatably mounted on said head, driving Connections between said shaft and each of said rings, said driving connections being arranged to constrain said rings to rotate in opposite directions relative to said head, and means for releasably holding either ring against rotative movement with said head to drive said shaft and thereby cause said spindle carrying member to move relative to said head.

In testimony. whereof I afiix my signature.

WILLIAM J. BAUMBERGER. 

